SECTION I SYMPOSIUM: Papers Presented at the Hip Society Meeting 2003
Treatment of periprosthetic femur fractures around total hip arthroplasty (THA) is challenging 1,3,16,17 because these fractures occur at a high stress area and often are associated with deficient or markedly damaged proximal bone. A validated classification system and treatment algorithms to treat periprosthetic femur fractures have been developed that provide guidance about the best form of treatment. 6–8,10,12 There is a general consensus that most fractures associated with a well-fixed stem (Vancouver Type B1 fractures) can be treated with open reduction and internal fixation 12,14 whereas most fractures associated with a loose stem (Vancouver Type B2 fractures) should be treated with revision arthroplasty. 20,21 Fractures associated with a loose stem and extremely poor proximal bone quality (Vancouver Type B3 fractures) typically have been treated with resection of the proximal femur and substitution with either a tumor prosthesis or an allograft prosthetic composite. 26
The main reason that Vancouver Type B3 fractures have been treated in this manner has been the difficulty of simultaneously gaining prosthesis stability and fracture fixation in the presence of nonsupportive proximal femoral bone. Fluted tapered uncemented implants now are available that allow the surgeon to gain axial and rotational control of the implant in the diaphysis of the femur distal to the profound bone loss and comminution frequently present in Vancouver Type B3 fractures. The efficacy of fluted tapered implants in revision femoral surgery has been shown in several series, mostly from Europe. 2,4,5,13 Experience with many types of fractures not associated with prostheses has shown that even badly comminuted damaged bone, when kept vascular, has the potential for a robust healing response. Recently, I used fluted tapered implants in combination with maintenance of a vascular proximal bone envelope to salvage Vancouver Type B3 periprosthetic femur fractures without resorting to an allograft prosthetic composite or a tumor prosthesis. The purpose of this study was to describe the technique and report early results of this approach for Vancouver Type B3 periprosthetic femur fractures. The primary aims were to assess fracture healing, short-term implant stability, and complications of the procedure.
MATERIALS AND METHODS
From 1999 to 2001, eight patients with acute Vancouver Type B3 periprosthetic femur fractures (seven patients) or a Type B3 periprosthetic femur fracture nonunion (Type B3 in one patient) were treated with a fluted tapered modular Ti grit-blasted femoral implant (Link MP™ Reconstruction Hip Stem, Waldemar Link, Hamburg, Germany). Three of the acute fractures occurred intraoperatively during revision of a loose stem with associated severe proximal femoral osteolysis and nonsupportive proximal femoral bone; the other four acute fractures were postoperative periprosthetic fractures associated with severe osteolysis many years after THA. This technique was used for all patients in my practice with a Vancouver Type B3 femur fracture and sufficient diaphyseal bone to gain fixation of a fluted tapered stem.
There were four men and four women with an average age of 68 years (range, 34–80 years). Six of the eight patients were 73 years or older. The socket also was revised in six of the eight hips. In one case of previous pelvic radiation, a bipolar hemiarthroplasty was in place preoperatively and a bipolar hemiarthroplasty also was used at revision. The other seven cases all were THAs.
The study was approved by my institution’s Institutional Review Board. Patients were identified using the computerized database and were analyzed retrospectively. All radiographs were evaluated by the author. Fracture healing was judged by evidence of bridging cortical bone present on AP and lateral radiographs. Prosthetic stability of uncemented stems was evaluated according to the criteria of Engh and Massin. 11 Patients were followed up routinely at 2 and 4 months, 1 year, 2 years, and yearly thereafter or at more frequent intervals as required clinically.
DESCRIPTION OF TECHNIQUE
Preoperative planning with templates was done to judge the approximate diameter and the length of the implant. In all patients the operative approach to the femur and the hip was done with the idea that the proximal femur would be exposed and the failed implant would be removed with minimum disruption of the femoral blood supply. Therefore, the upper femur was opened in all patients either by splitting the muscle along fracture lines and then opening the femur along existing fracture lines, or splitting the remaining intact portion of the upper femur with an osteotomy to gain direct access to the implant. In no patients were existing fragments of bone stripped of muscle. When necessary, osteotomies of the proximal femur were done using a modification of the techniques described by Wagner and Wagner 25 (Fig 1). For the modification of the Wagner technique, the proximal femur was split in a coronal plane with the osteotomy entering the tip of the greater trochanter and then extending down to the fracture. The medial cortex of the femur then was split either through existing fracture lines or by completion of the osteotomy medially with an osteotome or a saw, keeping the entire muscle envelope around the femur intact. The abductors were split approximately in their midportion for a distance of no more than 5 cm proximal to the tip of the greater trochanter to gain access to the hip. Soft tissue attachments to the fracture fragments were protected fastidiously. When fracture hematoma was present an effort also was made to maintain the fracture hematoma intact. The femur distal to the fracture site then was accessed directly by splitting the vastus lateralis, along fracture lines, to the level of the intact diaphysis.
The intact diaphysis was next reamed sequentially by hand with tapered stem reamers until it had been milled to support the cone of the tapered fluted prosthesis. When this procedure is done it is important to ream the femur relatively aggressively to gain a strong supportive cone for the implant. A prophylactic cable or wire then was placed around the femur just distal to the fracture site. Next, a fluted tapered grit-blasted Ti stem was impacted into the intact femur until it was rigidly stable to axial and torsional testing. The modular portions of the system were used to reproduce optimal proximal implant length and femoral component anteversion. After hip reduction, the proximal fracture fragments were pulled around the upper portion of the femur with limited use of cerclage cables and wires or sutures. An effort was not made to gain anatomic reduction of the many comminuted fracture fragments. Rather, the proximal prosthesis was used as an internal scaffold around which the fracture fragments were assembled loosely. When possible, an effort was made to gain continuity with cerclage or tension band wires between the main proximal fragments and distal fragments to tension the abductor mechanism. Throughout the procedure, the primary goal was to avoid devascularization of the proximal fragments by marked stripping of the muscular envelope. No strut allografts were used. Reamings from the patient’s own femur were packed along accessible fracture lines.
The postoperative regimen consisted of toe-touch weightbearing for 2 months, then partial weightbearing for 1 month, then progressive weightbearing for 1 month. Patients were allowed to advance off support at 4 months postoperatively as tolerated.
Patients were followed up by clinical examination and radiographs a mean of 1.5 years (range, 1–2 years) after surgery, with the exception of one patient with an acute fracture who died 1 week postoperatively of myocardial infarction.
The mean operative time was 244 minutes (range, 150–295 minutes).
There were no cases of stem subsidence and no patients had radiographic evidence of implant loosening. No stems have been revised for any reason.
All acute fractures were healed 1 year postoperatively. In all of the acute fractures there has been a robust healing response with marked increase in proximal bone probably related primarily to fracture callus (Figs 2, 3). The nonunion with a Vancouver Type B3 pattern had massive segmental proximal bone loss. Despite this, there has been considerable bone reconstitution around the implant.
Of the seven patients alive at latest followup, five had no pain, two had mild pain, and none had severe pain. Three patients walked with no support, two patients walked with a cane, and two patients used a walker.
Complications included death 1 week after surgery in one patient (noted previously) and two postoperative hip dislocations in one patient.
Vancouver Type B3 periprosthetic femur fractures around a THA are associated with weak nonsupportive and/or comminuted proximal femoral bone. These fractures are difficult to treat and most have been treated in the past with allograft prosthetic composites or tumor prostheses with sacrifice of the proximal femur. The goal of this study was to evaluate whether new uncemented fluted tapered prostheses in combination with preservation of proximal femoral bone could be used to treat these fractures successfully and gain fracture union and implant stability. Preliminary results show good implant stability, good clinical results, excellent fracture healing, and notable reconstitution of proximal bone. By comparison, of 18 patients who had revision surgery for periprosthetic fracture at my institution with an allograft prosthetic composite or tumor prosthesis (15 of the 18 had Vancouver Type B3 fractures), seven had failed results because of aseptic loosening (six patients) or infection (one patient) at a mean of 69 months. 24
The most important limitation of the study is that the results are early and require longer-term followup to show the efficacy of the technique. However, the patients have been followed up for a sufficient time to show fracture healing, which is one of the most important end points of such a study. Additionally, the patients also have been followed up long enough to identify marked reconstitution of the proximal femur and new bone formation despite preoperative severe bone loss and bony comminution. The fact that all of these uncemented implants have been stable in the short-term and the fact that the patients are functioning well clinically suggests the implants have gained biologic fixation and will remain stable for a long period. However, additional followup is necessary to document longer-term biologic implant fixation.
The technique described in this study derives from techniques that have been used previously, mostly in Europe, for revision surgery. Fluted porous tapered stems have the advantage of gaining uncemented fixation with rotational and axial stability distal to most fracture sites. Therefore, the surgeon is able to gain uncemented fixation in well-preserved diaphyseal bone well distal to the area of comminuted fracture. The efficacy of fluted grit-blasted tapered stems in revision surgery and their ability to gain long-term fixation has been documented previously. 2,4,5,13 At a mean of 4.8 years, Bohm and Bischel 5 reported on six failures in 129 revisions with the Wagner Self-locking Stem (Sulzer-Medico, Baar, Switzerland), and Bircher et al 4 reported a 92% survivorship at 10 years with the same implant. Despite these favorable results, numerous authors also have reported a rate of substantial subsidence with the Wagner stem. In the series of Isacson et al, 15 five of 22 hips subsided more than 2 cm and others also have reported that early subsidence can occur in some patients. 13,18 Published experience with fluted tapered Ti stems in revision hip arthroplasty, even in the absence of periprosthetic fracture, has shown the potential for bone reconstitution. 15,19,23 The method is predicated on the understanding that the modular stem must be strong enough to support high loads, potentially for long periods, even in the absence of good proximal bone support. 22
The difference between the technique described in this study and the traditional method of treating Vancouver Type B3 fractures is that the upper part of the femur is preserved and is allowed to reconstitute despite comminution and marked bone loss. The femur can be preserved in these circumstances because implants of this design gain their axial stability and rotational stability distal to the fracture site. Even though the bone of the upper femur may be damaged badly it is not used for implant support so it can be assembled loosely around the implant, thereby keeping the fragments’ vascularity intact, which promotes a healing response. I think the bone reconstitution seen in these cases relates in part to removal of the failed implant and return of function, and in part to a fracture healing response with callous. This technique requires that the operative approaches that are used minimally disrupt the bone’s blood supply by using existing fracture lines or new osteotomies, rather than by stripping soft tissues from the bone, to remove the failed implant and to place the new implant. Kolstad et al 19 reported early success treating nine periprosthetic femur fractures with the fluted tapered Wagner self-locking stem. Although the fractures were not categorized using the Vancouver system, they reported marked reconstitution of proximal femoral bone around the implant.
The limited bone grafting done in these patients is in distinction to techniques that use extensive cortical strut grafts around the femur. Cortical strut grafts tend to devascularize small underlying bone fragments. Nevertheless, cortical strut grafts can be useful in certain cases to gain additional mechanical stability of constructs around periprosthetic fractures, 9 and to augment deficient bone stock. Strut grafts are complimentary to the methods reported in this study. This study shows that in many cases the natural host bone fracture healing response, if undisrupted, also can be used to gain fracture healing, and preservation and reconstitution of the host femur.
Currently, I use this technique for most Vancouver Type B3 fractures, and for selected Vancouver Type B2 fractures and selected Vancouver Type B1 fracture nonunions. When distal bone loss extends well past the diaphysis of the femur, the technique is not applicable and it also is not applicable if bone quality and geometry of the remaining femur are too poor to support a tapered fluted uncemented implant.
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© 2003 Lippincott Williams & Wilkins, Inc.
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